Lined conduit joint



May 31, 1966 A. s. AHMAD 3,253,841

LINED CONDUIT JOINT Filed Deo. 5, 1963 Eis- 5 Il l ////l United StatesPatent O 3,253,841 LINED CGNDUIT JOINT Alan S. Ahmad, Dallas, Tex.,assigner to Avisun Corporation, Philadelphia, Pa., a corporation ofDelaware Filed Dec. 5, 1963, Ser. No. 328,250 1 Claim. (Cl. 285-55) Thepresent invention relates to a sealed joint for lined conduits.

A conventional and perhaps the most common method for rendering metallicconduits or pipes more resistant to corrosion involves spraying theinternal surface thereof with Ia suitable material, such as an epoxy,phenolic, polyester or polyurethane plastic material. -By exercisingcare yduring the spraying operation, the plastic material can be appliedso as -to provide for a continuous and unbroken coating along theinternal surface of a conduit or pipe. However, it is difficult withthis known method to determine whether the applied coating iscontinuous, unbroken and of uniform thickness. More important, suchapplied coatings are easily chipped at the ends of the conduits duringordinary handling. As a result, the exposed portions of the internalsurface of such conduit are subjected to the corrosive effects of thefluids which are being conveyed through the conduit, and further, oftenfacilitate the spreading of such corrosive iluids in-between the conduitIand the applied coating. Accordingly, a primary object is to provide agenerally new or improved and more satisfactory joint for linedconduits.

Another object of this invention is the provision of an improved linedmetallic conduit which provides for positive corrosion protection at theends thereof and which can be repeatedly re-used.

Still another object is the provision of an improved joint for linedconduit-s in which metals of different composition lare prevented fromcontacting each other or being exposed to the fluid which is to beconveyed therethrough.

These objects are accomplished in accordance with the present inventionby covering the internal surface of a metallic conduit or pipe with apreformed, continuous, non-metallic liner. Preferably the liner isformed of polypropylene in view of its chemically inert characteristics,and more important, its ability to be flared without rupturing duringits application to such conduit or pipe.

Preforrned liners are employed and are of such length as to project fromthe opposite ends of the respective conduits. Once inserted, the lineris locked against movement relative to the conduit after which itsprojecting ends are softened, as by heat, and then ilared upwandly andover the respective ends of the conduit. The applied liner `completelyshields the entire internal surface and ends of the conduit and ispreferably feathered at its ends so as to permit a coupling to be easilyapplied thereover.

The joint for the lined conduits includes a coupling which threadedlyconnects the adjacent ends of the lined conduits and a seal assemblyagainst which the ends of the lined conduits abut as the coupling isthreaded into position. The seal assembly includes a pair of rigidsleeves, which engage and maintain the ends of the conduit liners snuglyengaged with the ends of the respective conduits, `and an inwardlyprojecting insert or ring which is interposed between `the rigid sleevesand provides for a fluidtight joint. The rigid sleeves are preferablyformed of Monel or other materials which 4are resistant to theparticular fluid whichis to b'e conveyed through the lined conduits.While the insert maybe formed of polypropylene orpolytetrafluoroethylene resin Teflon or other chemically inert butflexible material. -If desired the rigid sleeves may be eliminatedwithout departing from the spirit or scope of the present invention.

In the drawing:

'FIGURE 1 is a sectional view taken longitudinally of a portion of aconduit in which a liner is about to be fixed;

FIGURE 2 is a sectional view taken longitudinally through a joint formedin accordance with the present invention; and

FIGURE 3 is a view similar to FIGURE 2 illustrating a modified jointarrangement.

With reference to the drawing, FIGURE 1 illustrates the end portion ofla conduit or pipe 11 which is to be lined with a preformed, continuousand unbroken polypropylene liner 13. The liner 13 is slightly smallerthan the conduit 11 in diameter but is of greater length so as toproject outwardly from the opposite ends thereof, as shown at 15.

At the start of the lining method, the liner 13 is locked againstmovement relative to the conduit 11 by an exe pandable mandrel or plug17, which includes a pair of wedge sections 19 and threaded operatingshaft 21. The wedge ysections 19 are loosely interconnected by links 23while the threaded shaft 21 is tapered at 25. Thus, as the shaft Z1 isadvanced further in-between the wedge sections 19 these sections are, ofcourse, urged apart and thereby frictionally lock the liner 13 againstthe internal surface of the conduit 11.

Once the liner 13 is locked in place, a heated flaring tool 27 is movedalong the shaft 21 and pressed against the projecting end of the liner13. The flaring tool 27 includes a -ring 29 which is heated by aresistance element 31, a bearing 33 which rides on the shaft 21, asleeve 35 for insulating the bearing 33 from the heated ring 29 andlinks 37 for moving the tool 27 along the shaft 21. Keys 39 are providedon the shaft 21 to permit the flaring tool 27 to be translated withoutrotating relative thereto.

As heretofore mentioned, one of the particular advantages of making theliner 13 from polypropylene is because of its ability to be ilaredwithout cracking or rupturing. Thus, as the heated aring tool 27 isurged against the liner 13 the projecting end thereof is' softened andilared outwardly and over the adjacent end of the conduit 11. Ofparticular importance is that the free end of the linel 13 is formedwith a feathered edge, as shown at 41, so that the liner 13 itself in noway interferes with the connection of such conduit to other linedconduits or pipe fixtures.

After both ends of the polypropylene liner have been ilared as describedabove, a pair of such lined conduits may be connected in a manner asshown in either FIG- URE -2 or 3. With the arrangement shown in FIGURE 2a seal assembly, indicated generally at 43, is interposed between theends of a pair of lined conduits 11 which are joined together by athreaded coupling 45. The seal assembly 43 includes a pair of sleeves 47and an insert 49. The sleeves 47 are formed of Monel, `or other metalwhich is resistant to the fluids which are to be conveyed through theconduits, and serve to maintain the flared ends of the liner 13 pressedsnugly against the adjacentends of the conduits 11. The insert 49, yonthe other hand, is preferably formed lof a chemically inert organicpolymeric material, such as polypropylene or polytetrauoroethylene resinTeflon and provides for a fluid-tight joint between the sleeves 47. ItWill be noted that insert 47 is shaped with flange portions 51 whichextend in-between the coupling 45 and lthe sleeves 47 so thatmetal-to-metal contact between these parts is prevented.

The joint arrangement shown in FIGURE 3 differs from that describedabove in that no sleeves are ernployed. In lthis modification, theadjacent ends of the lined conduits 13 abut against an insert 53, whichis the sa-me as the insert 49 described above, and are connectedtogether by a threaded coupling 55. The insert 53 serves .the dualfunction of maintaining the flared ends of the liner 13 engaged with therespective ends of the conduits 11 and to provide for a fluid-tightjoint. ment is thus better suited for less rugged duty than the conduitjoint shown in FIGURE 3.

Of particular importance is that the continuous and unbroken liner ofpolypropylene is not readily chipped or cracked. Thus, thelined conduitcan withstand rugged and repeated handling and use without risk ofdamaging the end portions of the liner and possible exposure of theinside surface of the conduit. Further, it will be noted that in both ofthe joint arrangements illustrated none of the internal surfaces of theconduits are exposed to the fluids to be conveyed therethrough.Additionally, the joint arrangements insure that no dilicerent metalscontact with each other or are exposed to the fluid which is t-o beconveyed so that the possibility of electrolytic corrosion of theconduits or connecting members is corn- -pletely avoided.

It is to be understood that changes and variations may rbe made withoutdeparting from the spirit and scope of the invention as defined intheappended claim.

I claim:

A joint including at least two metallic conduits disposed in end to endrelationship, a preformed, unitary, non-metallic liner positioned withinand extending beyond the ends of each of said conduits for protectingthe same against the corrosive action of iluids which are to beconducted therethrough, said liners each being flared outwardly and overthe ends of the respective conduits and provided with feathered edges, asealing assembly interposed between and abutted by the adjacent Thearrangeends of the lined conduits, said sealing assembly including aring formed of non-metallic material which is inter posed between andinterlocked with a pair of corrosion resistant metal sleeves, said'sleeves each having portions which extend into yan adjacent linedconduit and being of substantially the same inside diameter as saidring, and a coupling threaded onto the ends of said lined conduit andenclosing said sealing assembly for main-taining said sealing assemblyand conduits in substantially ixed relationship.

References Cited by the Examiner UNITED STATES PATENTS 1,615,536 v1/1927Del Mar 2 285-371 2,086,151 7/1937 Bannerman 285-55 2,148,747 2/1939Hampe 29-157 2,613,958 10/1952 Richardson 285-55 2,805,872 9/1957 Routh285-55 y3,047,937 8/1962 De Vecchi 29-157 3,142,499 7/1964 Lang 285-553,199,879 8/1965 Fleming.

FOREIGN PATENTS 881,192 1/1943 France.

883,048 3/ 1943I France. 1,268,406 6/ 1961 France. 1,022,860 1/ 1958Germany.

`CARL W. TOMLIN, Primary Examiner.

R. A. GIANGIORGI, Assistant Examiner.

